Commercial deep fryers are commonly used in fast food restaurants to cook food items such as fries, chicken, etc. Most of these fryers include a reservoir of cooking oil that is heated to a predetermined temperature. In many of these fryers, the oil is heated by a gas burner which fires into a heat exchange tube that passes through the cooking oil reservoir. The flame and combustion products heat the wall of the heat exchange tube which, in turn, transfers this heat to the cooking oil.
Gas-fired fryer designs require very rapid heat release (short flame) in order to take advantage of the very short heat exchange tube/chamber that is typically found in a fryer design. These factors generally require high levels of primary aeration and a relatively large burner outlet. Because of the relatively small space available in a deep fryer, the gas burners used in these appliances need to have an inlet that is at some angle to the burner outlet which may be up to 90° in some cases. In order to maintain a high primary aeration, the burner has to be very free flowing or have very little internal restriction to flow. It is also important to balance the flow of the gas/air mixture through the discharge end of the burner in order to maintain a consistent temperature profile and good secondary air distribution for clean combustion. Balancing the flow is difficult because it involves putting a restriction into the burner in areas of high flow, which reduces burner performance due to lower primary aeration.